Exercise effects on arterial stiffness and heart health in children with excess weight: The SMART RCT

INTRODUCTION: Childhood obesity and inactivity are associated with cardiovascular risk. Evidence is limited for exercise effects on arterial health in children. METHODS: One hundred seventy-five inactive children with overweight or obesity (8–11 years, ≥85th percentile BMI, 61% female, 87% Black, 73% with obesity) were randomized to an 8-month daily after-school aerobic exercise program (40 min/d, n=90) or a sedentary control condition (n=85). Carotid-femoral pulse wave velocity (PWV, primary outcome, arterial stiffness), fitness, adiposity, blood pressure (BP), glucose, insulin resistance, lipids, and C-reactive protein were measured at baseline and posttest (8 months). Adiposity, fitness, and BP were measured again at follow-up, 8–12 months later. Intent-to-treat analyses were conducted using mixed models. RESULTS: The study had 89% retention, with attendance of 59% in exercise and 64% in the control condition, and vigorous exercise participation (average heart rate 161±7 beats/min). Compared to controls, the exercise group had twice the improvement in fitness (VȮ(2) peak, 2.7 (95% CI 1.8, 3.6) vs. 1.3 (0.4, 2.3) ml/kg/min) and adiposity (−1.8 (−2.4, −1.1) vs. −0.8 (−1.5, -0.1)%), each p=0.04, and a large improvement in HDL-cholesterol (0.13 (0.075, 0.186) vs. -0.028 (−0.083, 0.023) mmol/l, p<0.0001). There was no group×time effect on other outcomes at 8 months, or on any outcomes at follow-up. The change in PWV at 8 months correlated with changes in insulin and insulin resistance (both r=0.32), diastolic BP (r=0.24), BMI (r=0.22) and adiposity (r=0.18). CONCLUSIONS: Eight months of aerobic exercise training improved fitness, adiposity, and HDL-cholesterol levels, but did not reduce arterial stiffness in children with excess weight. PWV improved as a function of insulin resistance, BP, BMI and adiposity. Weight loss may be required to improve arterial stiffness. Exercise benefits waned after discontinuing the program. TRIAL REGISTRATION: This study is registered at www.clinicaltrials.gov NCT02383485.